Premium
Synthesis, crystal structure and properties of a quaternary oxide with a new structure type, BiGaTi 4 O 11
Author(s) -
Yamane Hisanori,
Yagi Ryota,
Hosono Akira,
Masubuchi Yuji
Publication year - 2019
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229619005989
Subject(s) - dielectric , band gap , analytical chemistry (journal) , bismuth , materials science , crystallite , oxide , octahedron , single crystal , electrical resistivity and conductivity , activation energy , crystal structure , mineralogy , crystallography , chemistry , metallurgy , optoelectronics , chromatography , electrical engineering , engineering
A new quaternary oxide, BiGaTi 4 O 11 (bismuth gallium tetratitanium undecaoxide), was prepared by heating a mixture of the binary oxides at 1373 K in air. BiGaTi 4 O 11 melts at 1487 K and prismatic single crystals were obtained from a sample melted at 1523 K and solidified by furnace cooling. The structure of BiGaTi 4 O 11 was analyzed using single‐crystal X‐ray diffraction to be of a new type that crystallized in the space group Cmcm . A Bi 3+ site is coordinated by nine O 2− anions, and three oxygen‐coordinated octahedral sites are statistically occupied by Ga 3+ and Ti 4+ cations. A relative dielectric constant of 46 with a temperature coefficient of 57 ppm K −1 in the temperature range 297–448 K was measured for a polycrystalline ceramic sample at 150 Hz–1 MHz with a dielectric loss tan δ of less than 0.01. Electrical resistivities measured at 1073 K by alternating‐current impedance spectroscopic and direct‐current methods were 1.16 × 10 −4 and 1.14 × 10 −4 S cm −1 , respectively, which indicates that electrons and/or holes were conduction carriers at high temperature. The optical band gap estimated by the results of diffuse reflectance analysis was 2.9–3.0 eV, while the band gap obtained from the activation energy for electrical conduction was 3.5 eV.